The subject matter disclosed herein relates to the art of spraying and, more particularly, to a spray gun having multiple independently controllable nozzles.
Conventionally, spray techniques are generally used to provide a surface treatment to a component. Cold spray techniques, for example, are employed when it is desired to apply a coating without adding heat or the like to affect a bond between the component to be coated and a coating material. Other applications for cold spraying include constructing free-form structures.
Cold spray techniques utilize a cold spray gun that delivers particles onto a surface at high velocity. The particular velocity used is generally dependent upon the particles being sprayed. Harder particles require spraying at higher velocities to ensure adhesion while lower velocities may be acceptable to facilitate adhesion of softer particles. As soft and hard particles required different velocities, cold spraying composite materials presents various challenges. Currently, there are two techniques for achieving a cold sprayed coating formed from hard and soft particles. In one technique, a first layer is formed by applying either hard or soft particles. After applying the first layer, a second layer including the other of the hard and soft particles is applied. In another technique, hard and soft particles are mixed to form a composite mixture that is delivered into a surface. An application velocity for the composite material is chosen that facilitates adhesion of the harder particles without causing damage to the softer particles. Often times, establishing a velocity that achieves both goals is not possible.